Obesity in U.S. projected to grow, though pace slows: CDC study

The proportion of obese Americans is forecast to climb to 42% by 2030, according… (Jeff Haynes / AFP/GettyImages )

Obesity in the United States is projected to continue its rise over the next 18 years, extending to 42% of Americans by 2030, according to a study released Monday by the Centers for Disease Control and Prevention.

That expected growth in the proportion of obese Americans -- up from 34% -- contained good news and bad: Obesity's growth has slowed from the record-setting pace that has marked most of the last three decades; at the same time, the numbers of the severely obese -- those carrying 80 or more pounds more than the healthy, normal weight for their height -- is expected to grow by 130%.

The continued growth in obesity will be expensive, said CDC statisticians: Additional spending on healthcare for Americans who will join the ranks of the obese in the next 18 years was projected to reach $549.5 billion over the next two decades.

By the most current obesity statistics, 35.7% of American adults -- 78 million people -- and 16.9% of U.S. children and adolescents -- 12.5 million kids -- are obese, meaning their body-mass index is 30 or over.

The new projections capture several trends in American society: the swelling population of Latino adults, among whom obesity is a growing problem, the transition into adulthood of a population of obese children -- especially African American boys -- who stand a high likelihood of becoming obese adults, and the aging of overweight and obese adults, who are far more likely to take on more weight than to lose as they get older.

In a bit of good news, the obesity rate among women was flat. Currently, 35.8% of American women are considered obese, and the forecast released Monday does not predict a significant change in that level.

Still, the projected 33% rise in obesity is rosier than the 51% rise that had been projected by statisticians assuming a continued level of the roaring growth seen in the 1980s, 1990s and early 2000s. "This and other forecasts likely overstate future obesity prevalence given the recent evidence of slower growth," wrote Duke University global health professor Eric A. Finkelstein and co-authors in a forecast of the nation's weight problem close to 20 years out.

In a news conference that was the centerpiece of a second annual "Weight of the Nation" conference in Washington, D.C., Finkelstein said it was unclear whether the galloping rate of growth has slowed because of public policy initiatives aimed at preventing child obesity, greater societal awareness of obesity's risks, or because Americans have hit the maximum level of fatness a population can sustain.

"The slope has changed," he said. Statistically, he noted, "it doesn't take much" for obesity prevalence to rise from 34% to 42% in 18 years.

By the same logic, the authors of the projection noted that even small successes in anti-obesity efforts -- new, more effective weight-loss drugs, communities and campaigns designed to encourage more exercise and healthier eating, work-site health-promotion policies -- could flatten the upward curve.

"Even small improvements in obesity prevalence ... could result in substantial savings," they added. The projected $549.5-billion healthcare bill represents the difference between providing healthcare for a population with 34% obesity and a population whose obesity prevalence has risen to 42%.

The CDC forecast took into account a host of factors thought to influence Americans' eating and exercise habits, including the cost of groceries, the density of restaurants, rates of unemployment, Internet access and the price of gas. Most important, however, was the aging of the population, which tends to nudge many overweight adults into the obese category, and to push a growing number of those who are already obese into "severely obese" territory.

"Long-term, sustained weight loss" in adults who have become obese, said Finkelstein, "is elusive."

Finkelstein and his co-author, health economist Justin G. Trogdon of RTI International, cautioned that despite their detailed modeling of factors that influence obesity, forecasting fatness in a future population "is tricky business." While tendency to exercise, access to healthy food and convenience of high-calorie fast food all influence a population's propensity to gain weight, such factors stand alongside far more powerful influences, such as genetics.

"They're estimates, but like any estimates, are they going to be accurate?" Finkelstein asked Monday. "Well, time will tell."